The present invention relates to a disc brake and more specifically to an actuator for a disc brake for automotive vehicles.
The actuator of the present invention is particularly applicable to a disc brake of the floating caliper type wherein friction lining pads in the form of ring sections are carried by the caliper on opposite sides of a rotatable disc and are axially movable into contact with friction braking surfaces provided to a disc mounted for rotation with a vehicle wheel. In that type of brake, the pads are moved by an actuating mechanism or actuator which in turn is driven by a fluid motor. Brake systems powered by pneumatic pressure have been readily accepted for commercial vehicles since the required brake actuating force can be rapidly developed adjacent each wheel or wheel set using relatively compact air motors.
Since the total force available for application to the friction braking surface is dependent on the force required to operate the actuating mechanism, it is desirable to utilize an efficient actuating mechanism. This is particularly true in disc-type brake systems where the pressure required between the friction pads and the rotor is greater than the pressure required between the friction braking surfaces in drum-type brake systems.
Moreover, since the interfacing friction lining and rotor braking surfaces are substantially planar, parallel surfaces, it is also desirable to move the friction lining pads in a direction normal to the rotor braking surfaces and to bring the entire friction lining surface of each pad into contact with the rotor braking surface at one time under substantially uniform pressure to prevent uneven wear of the linings.